Pebcussiow-dkill



L. L. scofi.

PERCUSSION DRILL. APPLICATION Fl LED JUNE 13. 191B.

1 ,3 O8,8 1 1, Pzitented July 8, 191.9.

WITNESS C IN V'EJV TOR.

' Lewis LScofi ATTQRNEY.

nEw'Is L. seor'r, on ST. Louis, mrssounr.

PERCUSSION-DRILL.

Specification of Letters Patent.

Patented J uly 8, 1919.

Application filed June 13, 1918. Serial No. 239,718.

Toall whom it ma concerns .Be" it known t at I, LEWIS L. Soon, a

citizen of the United States of America, re-

siding at the city of St. Louis, State of Missouri, United States of America, have invented a'certain new and useful Percussion- Drill, of which the following is such a full, clear, andexact description as will enable any one skilled in the art to which it appertains to make and use the same, reference being bad to the accompanying drawings forming part of th1s speclfication;

My invention relates to a percusslon drill and has for its object the production ofa.

drill in which the drill bit is actuated by a free piston which in its'forward stroke is unconnected with the other moving parts of the drill, whereby a quicker and more effective blow may be-imparted to the drill bit than is ossible where the piston actuating the bit 18 connected with the crank shaft. 1

. Another object of my invention is to pro.-. vide'manually operated means whereby the free piston may be thrown out of-operation.

In the accompanying drawing WhlCh lllustrates'one form of drill made in accordance with my invention, Figure 1 is a longitudipal sectionand Fig.2 is an enlarged cross section taken on the line 2-2 of Fig. 1.

5 indicates the casing of the drill in which is arranged a piston 6 connected by means of a rod 7' with a crank shaft 8 journaled in the casing 5. The casing 5 together with the piston 6 forms an internal combustion engine of the twocycle type and the p1ston 6 is provided with the usual-deflecting plate 9 for deflecting the charge which enters the combustion chamber 10 through a bypass 'ada ted to be uncovered when the piston 6 reac es the near end-of its stroke. The fuel is drawn into the crank case 12 through an opening 13 cpnnectedto any'suitable fuel er vlded w1th the usual spark plug 14 for lgniting the charge. a

The charge in the combustion chamber 10 is adapted not only to actuate the pistonlG but also to actuate a free piston 15 which is arranged in the casing 5 in advance of the piston (ii-Piston 15'is'prov1ded w1th an anvil 16 ada ted to strike against the inner end ,of the dri bit 17 in order' to actuatethe same. In order that the charge may be compressed in the combustion chamber 10 between the forward end of the piston 6 and the rear end I of thepiston 15, I provide the casing 5 with The combustion'chamber 10 is prop a detent 18 normally held in the path of the piston 15 by means of a coil spring 19 .crank shaft 8. The cam 21 is held against rotation relative to the rod 22 by means of a cam 21 to be moved longitudinally of the shaft 22 by means of a milledhead 26 so as to move the said cam 21 out of engagement with the cam face 20 on the detent 18. The

discharge passage 27 leading frlom the combustion chamber 10 is of comparatively large cross section and is adapted to discharge into the forward end of the chamber 28 containing the free piston 15 after which the products of combustion are discharged into the air through a passage. 29 of less area than the passage 27 so as to cause an excess of pressure in the forward end of the chamber 28 to assist in returning the piston 15 to normal position, as will hereafter be more fully described. 30 is a light coil spring arranged in front of the piston 15. i

The operationof my drill is as follows: The charge is drawnin through the opening 13 when the piston 6 moves forward and is compressed in the chamber 12 when the said piston 6 moves toward the rear. Upon reaching the rear limitrof its movement the bypass is uncovered to allow the charge to piston 15 is held in position as shown in.

Fig. 1 of the drawings by the engagement of the detent 18 with its forward face. At or just afterthe time that the charge is exloded by the action of the spark plug 14, the detent 18 is withdrawn so as to allow the piston 15 to be forced freely forward by the explosion of the charge to cause its anvil 16 to strikeagainstdthe end of the drill bit 17. The recoil caused by the striking of the drill bit 17 together with the action of the spring key 25. This key 25, however, allows the' 30 throws the piston 15 back toward .its initial position and this movement is assisted by the discharge of the contents of the combustion chamberlO through the discharge passage 27 into the forward end of the chamber 28. i

In case it is desired to operate the pis- I ton 6 without operating the free piston 15,

as for instance,-in withdrawing the drill, the milled head 26 is moved rearwardly along the shaft 22 so as to move thecam; 21 out of engagement with the cam face 20 so that the detent 18 will not be withdrawn.

It will be understood that the forward end of the shaft 22 is used to rotate the drill bit 17 through any suitable mechanism which is not shown, as it forms no part of the present invention.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a percussion-drill, a cylinder, a piston in said cylinder, a drill bit, a second piston movable independently of saidfirst named piston and actuated by the same charge, said second piston being adapted to strikev said drill bit, and means for lockingsaid second piston during alternate strokes of said first piston.

2. In a percussion drill, a pair of pistons,

, a combustion chamber communicating motionto both said pistons, a crank shaft connected to one of said pistons, and retaining means for the other of said pistons controlled from said crank shaft.

3. In a percussion drill, the combination of a pair of pistons, of a combustion chamber for actuating both of said pistons, a crank shaft operatively connected to one-of said pistons, a detent for the other of said istons and means 0 erated' from said crank p a operatively connected to oneof said pistons, a drill bit adapted to be struck by the other of 'said pistons, a detent for said second named piston, and operative connections between said crank shaft and detent for controlling the latter.

5. In a percussion drill, the combination with a compression piston, of a free piston,.

both of said pistons being actuated from' the same combustion chamber, locking means for retaining said free piston during the comfree piston.

.6. In a percussion drill, the combination with a compression piston, of a free piston,

7. In a percussion drill, the combination with a compression piston, of a'free piston, both said'pistons'being actuated from the same combustion chamber, locklngmeans for positively retainingsaid free piston in position during the compression of the charge, and a spring operating on said free piston to assist in returning the same to normal position.

8. In a percussion drill, the combination with a compression piston, ofa free piston, both said pistons being actuated from the same combustion chamber, a crank shaft connected With said compression piston, a detent for said free piston controlled by said crank shaft, and manually operated means.

for throwing-said control. out of operation. In testimony whereof, I have hereunto set my hand and affixed my seal.

LEWIS L., SCOTT. [14s.]

'pression of the charge in the combustion. chamber, and a drill bit actuated from said 

